Process of nitrating ethane



Feb. 16, 1937. H. B. HAss ET AL PROCESS 0F NITRATING ETHANE Filed May 16, 1936 Tag.

Patented Fei). 16, '1937 l 2,071,122

UNITED STATES PATENT ori-ICE 2,071,122 PROCESS F NTTRATmG ETHANE Henry B. Hass, West Lafayette, andl Edward B. Hodge, Terre Haute, Ind., assignors to Purdue Research Foundation, West Lafayette, Ind., a corporation of Indiana Application May 16, 1936, Seal No. 80,070

8 Claims. (Cl. 2260-144) It is the object of our invention to' effect the and preferably between 300 C. and 500 C. We nitration of ethane.V nd that about 420 C. gives good results. This In Patent No. 1,967,667, of July 24, 1934. grantheating is desirably obtained by having the reed to us in association With Byron M. Vanderbilt, action tube I3 immersed in a bath containing a 5 there was disclosed for the first time the vapormolten salt mixture that is maintained at such y, phase nitration of saturated aliphatic hydrocar. temperature. A suitable mixture for this is a bons having from'.3 to 8 carbon atoms; but that eutectic mixture of sodium nitrite and potassium application was limited to hydrocarbons within nitrate. The temperature mentioned is suithat range, in which in addition to primary carciently high to keep both the reagents and the bon atomsthere were also secondary and/or reaction products in gaseous phase. 'I'he vapo- 10 tertiary carbon atoms; for vthe nitration at the rized nitric acid is in part decomposed when specific temperatures there named tended to ocheated, and yields various decomposition prodcur principally on tertiary carbon atoms, and to ucts, among which is nitrogen dioxide. That somewhat smaller extent on secondaryv carbon nitrogen dioxide undoubtedly enters into the niatoms, while it occurred only to a relatively small tration reaction with the ethane. 15 extent on primary'carbon atoms. There was no The supply of ethane is desirably such-that indication at the time of the application for that the passage of the gases through the reaction patent, or from the disclosure of that patent, that tube permits the nitration'to occur without leava similar nitration could be obtained with ethane, ing any substantial amount of nitrogen dioxide in which only primary carbon atoms are present. in the exit gases. To determine this the speed 20 We have now found that even with ethane, of gas passage is increased until appreciable which has no secondary or tertiary carbon atoms, amounts of nitrogen dioxide appear in those exit nitration is possible by a process otherwise largegases; and then the rate of ow is gradually dely like that shown in said Hass, Vanderbilt and ,Y creased until the nitrogen dioxide has just dis- Hodge Patent No. 1,967,667; and to do this for appeared from the exit gases. We nd this to the most advantageous reaction it is desirable be approximately the optimum velocity of flow.

that the temperature be raised above the 135 to The mixed gases from the reaction tube I3 300 C. mentioned in that patent (although some are passed through a cooler I5, in which they Anitration can be obtained at that range of temare cooled vsufilciently to condense most of the peratures) and brought to ,somewhere between nitroethane which has been formed. When the 30 300 and 500 C. f operation is conducted at atmospheric pressure,

A suitable apparatus for doing this by acon- 0 C. is a satisfactory cooling temperature for tinuous process is that shown inthe accompanythis cooler I5. ing drawing. In that drawing, Fig. 1 shows di- In this nitration, it is found that some nitroagrammatically an apparatus in which vapors methane accompanies the nitroethane in the 35 of heated nitric acid are used to produce the niexit gases. Perhaps this is because of the fortration; and Fig. 2 shows fragmentally a modimation'of acetic acid, and its subsequent nitra- 1 cation in which nitrogen dioxide is supplied -as tion and decarboxylation. It may also be due such for that purpose instead of by the heating to the addition of nitrogen dioxide to methyl of nitric acid. radicals which mayibe present. 40

Ethane at atmospheric pressure is supplied The condensed liquid from the cooler I5, with through a pipe I0 in vapor phase, and in the apany accompanying gases, passes to a liquid-gas paratus of Fig. 1 is`bubbled through hot concenseparator I6, in which the condensed nitroethane trated nitric acid in a suitable container II. The and spent acid are removed from the unconconcentration of nitric acid vapor in the hydrodensqi gases. The liquid separated in the sepa- 45 carbon is' determined by the temperature of the rato?` I6 separates in turn into two layers, one nitric acid in the container I I; for by maintainof which consists of the spent nitric acid and ing this temperature at about 108 C. and carrythe other of which consists essentially of nitroing on the evaporation at atmospheric pressure ethanewith some nitromethane. These layers about one mole of nitric acid is vaporized for may be drawn off at different levels, or the 50 each two moles of ethane, whichv we nud to be whole drawn oi and the two layers separated a satisfactory ratio. The mixture of lethane and by decantation. The nitroethane can be purinitric acid vapor passes from the container Il by ded, if desired, by washingvwith water and rectia pipe I2 to a reaction tube I3 .which is suitably cation under atmospheric or sub-atmospheric heated to a temperature at least above 150 C. pressure. 'I'he gases from the separator I6. con- 55 l May be and desirably is recycled;

sist of ethane, nitric oxide, carbon monoxide. carbon dioxide, water vaporand somevapor of nitroparaiiins. These gases and vapors may be taken off through the pipe I9 which leads from the upper part of the separator I6, and carried by that pipe to any convenient apparatus for the separation of the'component gases.

The nitric oxide is preferably reconverted to nitric acid or to nitrogen dioxide, for further use in this process; and the separated ethane If desired, the whole operation may be carried on under a pressure which is sulcient to cause liquefaction of ethane in the cooler I5.

Instead of vaporizing and decomposing nitric acid, which yields nitrogen dioxide, we may supply nitrogen dioxide as such. This is shown in Fig. 2. There ethane is supplied as before by a pipe I0, desirably a valve pipe, but is supplied directly therefrom to the pipe I2. Nitro-- gen ldioxide is also supplied to the pipe I2 by a valved pipe 20. The valves are adjusted so that there will be a sucient excess of ethane to avoid explosion. The remainder of the apparatus is as in Fig. 1.v

We claim as our invention:

1. The process of nitrating ethane, which consists in producing contact between ethane and nitric acid with both reagents in the gas or vapor phase. v

2. The process of nitrating ethane, which'consists in producing contact between ethane and nitric acid with both reagents 1n the gas or vapor phase and at a temperature between 300 and 500 C.

3. The process of nitrating ethane, which consists in producing contact between ethane and nitric acid with both reagents in the gas or vapor phase and at a. temperature above 150 C.

4. The process of nitrating ethane, which consists in producing contact between ethane in the gas or vapor phase and the gases or vapors formed by heating nitric acid.

5. The process of nitrating ethane, which consists in producing contact between ethane in the gas or vapor phase and the gases or vapors formed by heating nitric acid and at a temperature between 300? and 500 C.

6. The process of nitrating ethane, which consists in producing contact between ethane in the gas or vapor phase and the gases or vapors formed by heating nitric acid and at a temperature above 150 C.

7. The process of nitrating ethane which consists in producing contact between ethane and nitrogen dioxide at a temperature above 150 C.

8. 'I'he process of nitrating ethane, which consists in producing contact between ethane and a compound in the class Yconsisting of nitric acid and nitrogen dioxide, with both reagents in the gas or vapor phase.

HENRY B. Hass. EDWARD B. Hopen. 

